If there are no slots in the valve cover(1955 and later) it should have a vented oil filler cap on the valve cover. I would make sure that is clean or buy a new one.
As for the road draft tube I burn them out. If you have a wood stove you can put it in the fire until it gets red hot, then let it cool and blow it out. I use a Propane weed burner installed in the tube to burn them out.
Someone may get on here and say there is horse hair in the tube that will burn out, but I have cut a number of them apart and have found nothing, so burning them out is fine.
